This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Cyanophenylalanine (PheCN) has found many applications in infrared spectroscopic studies of protein folding dynamics due to the strong and spectrally isolated nitrile vibration. Recently we discovered that PheCN we recorded visible absorption and emission spectra and found good fluorescence property of this modified aminoacid. Typically, absorption is in the 270nm region and emission maximum around 310nm. We propose to use in protein folding studies as a local chromophor, especially in the study on the effect of D-amino acids on the folding dynamics of Trp-cage. D-amino acids are commonly used in protein design to enhance protein stabilities. However, the kinetic role of D-amino acids in protein folding has not been studied. Thus, the goal of this project is to use a small folding motif, Trp-cage, to systematically examine the effect of individual D-amino acids on the folding kinetics of the protein.